Automatic and semiautomatic telephone system



March 1s, 1930. R, TRECHQNSK. 1,751,431

AUTOMATIC AND SEMIAUTOMATIC TELEPHONE SYSTEM Filed April 28, 1928 Patented Mar. 18, 1930 UNITED STATES PATENT .l oFFIcE ROMAN TRECI-ICINSKI, OF' WARSAW, POLAND, ASSIGNOR T0 TELEFONAKTIEBOLAGET Y L. M. ERICSSON, OF STOCKHOLM, SWEDEN, A COMPANY OF SWEDEN AUTOMATIC AND SEMIAUTOMATIC TELEPHONE SYSTEM Application iiled April 28, 1928, Serial No. 273,750, and in Sweden May 2, 1927.

The object of the present invention is t provide inter-oiiice traiic between automatic telephone exchanges of the kind in which the selectors are set by means of current impulses sent in a forward direction in synchronism with the impulse sending from the subscribers station, on the one hand, and such exchanges in which the selectors areset by means of revertive or back-impulses, controlled by a register, on the other hand.

change. Assuming that the calling subscriber must be able to vsend the current impulses quite independent of the switching operations in the exchanges, the arrangement should be disposed in such a manner that a register always is standing by, readyl to receive the impulses as soon as a junction line is engaged. This problem can be solved in the easiest manner by providing each junction line with a separate register. As a register, however, is a comparatively expensive apparatus and, furthermore, is in use only during the establishment of the telephone connection, it is desirable to use a smaller number of registers which are common to a larger number of junction lines. This is made possible according to the present invention by arranging those registers which are common to one group of junction lines in such a manner that they are connected automatically immediately after the completed setting of the selectors, to another line Y which is free at that moment and to which prising a circuit arrangement according to the invention.

lThose parts of the telephone connection which appertain to different exchanges are separated by a dashed and dotted line L1. On the left hand side of this line there is shown a group selector GV, appertaining to an exchange which, by way of example, can be built according to the known Strowger system, see for instance the United States Patent 815,176 Keith and Erickson Marchfl, 1906 whereas those parts which are placed on the right hand side of said line appertain to an exchange of such a kind in which thetelephone connections are established by the intermedium of a register, see for instance the United. States Patent 1,580,321 vPalmgren April 13, 1926. The junction line a, Z), c between these two stations terminates in the latter exchange in another group selector GV2. The registers can be of any suitable type for instance ofthe type described in the shown inside a'dashed and dotted line L3. Said Searcher can be of the machine driven type and is provided with a clutch magnet-S for coupling the shaft of the searcher to a continuously rotating shaft. The shaft of the searcher is provided with six contact arms which are intended to make contact with certain contacts in a corresponding number of contact rows A, B, C, D, E, F in such a man-` ner that the two opposite contacts in each separate Contact position are electrically connected through the corresponding contact arm.

A free register connects itself automatically to a free junction line in the following inan-V ner. All junction lines which are not engaged by a conversation and to which a register is not already connected, are marked as free in the searchersthereby that the relay DB4 is deenergized, the corresponding contact in the contact row F being connected to the negative pole of the battery over a re'- sistance R1. As long as the searcher moves over contacts which are not markeo` in such a A manner, the clutch magnet S remains energized over a contact ot a testing relay BB1. wWhen the searcher linds a junction line which is marked as free, the relay is energized over the circuit l and the said contact is interrupted and the searcher stops. During the movement or' the Searcher also a relay BH2 has been energized over the same contact of the relay RJ11. lil/Then the relay RRQ is deenergized, a circuit is closed through a relay DB1 a relay dit and a Contact 761 of a sequence switch appertaining to the group selector Gila The relay GR locks itself over a contact 3 and the DB1 marks the junction line as free at the group selector @V1 by disconnecting the o-wire from the battery. Previously the junction line had been marked as engaged because the c-wire was connected to the negative pole of the battery over a resistance R2. The junction line is thus now ready to receive a call. During the lapse oit time when the register remains connecten to the unction line, the latter is marked as engaged for other registers by the drop of volt age in the resistance B1 which issuicient to prevent the excitation of another testing relay which is connected into circuit in parallel with the relay BB1.

The connection to a junction line which is marked as free, through the group selector G-V1 is established in a manner known per se. After the contact arms ot the group selector have been raised to that contact row to which the junction lines in question are connected the searching of a tree trunk line is effected by turning the contact arms. The turning movement is started by a current impulse through the winding SL in a magnet SPM of a sequence switch. Then a rotary magnet DM is connected into an impulse circuit containing an interrupter UR. lf the first junction line is engaged the magnet SPM remains energized over a circuit 4L which is not interrupted until when the selector finds a free junction line. When the magnet SPM is deenergized, the arm SR of the sequence switch is moved to its third position, the junction line being thus marked as engaged for the second group selector GV1 as the o-wire is then connected to the negative pole of the battery through a release relay SR and a contact 5 which was closed when the selector lett the normal position.

The following current impulses which are sent over the a-branch of the junction line actuate a. relay DR2 which controls an impulse circuit 6 containing an impulse relay BB3 at the register. The register is thereby set in accordance with the impulses sent. The completion of the telephone connection takes place under the control of the register in a manner known per se. After completed connection the register is returned to the normal position. During the return period the contact 7 ot the register is interrupted while another contact 8 remains closed. rlhen a circuit 9 is closed through a relay DR3 which is energized and in turn closes a circuit 10 tor a relay DB1. The latter relay marks the unction line as engaged for the registers. As long as the relay DB3 is operative the relays DB1 and GR are energized over a contact 13 independent orp the searcher. The register sender is now started and connects the register in the above described manner to another junction line. W hen the relay DB3 was energized the two windings AL, BL of a relay DB5 were connected into the line circuit, which relay is now energized and connects the relay DR3 into a retaining circuit over the contacts 1l and l2. l/Vhen the line circuit is interrupted after a completed conversation the restoring magnet SR receives a current impulse over the circuit la and the telephone connection is interrupted in known manner. The circuit `for the relay DB3 is then interrupted at the contact 12 whereupon also the relays DB1, DB1 and GR are cle-energized.

l claim:

l. In a telephone system the combination of subscribers lines, junction lines, means for connecting a calling subscribers line to a disengaged junction line, automatic switches for further extending the telephone connection from said junction line, registers for controlling the setting of said switches, automatic switching means for connecting an idle register to a junction line, andmeans under the control of a register for causing this register to be automatically connected to a disengaged junction immediately upon the register being set free for other connections.

2. ln a telephone system the combination of subscribers lines, junction lines, means for connecting a calling subscribers line to a disengaged junction line, automatic switches for further extending the telephone connection from said junction line, registers for controlling the setting of said switches, automatic switching means for connecting an idle register' to a junction line, means under the control of a register for causing this register to be automatically connected to a disengaged junction immediately upon the register being set free for other connections, and means under the control oit' a register for marking a junction line as available for a calling subscriber only upon an idle register being connected up to the junction line.

3. In a telephone system the combination ot subscribers lines, junction lines, selecting means for selecting a disengaged junction line, means for establishing connection between a calling subscribers line and a disengaged junction line, means for marking a junction line as non-accessible to said selectn ing means when there is no register con-4 nected to the junction line, automatic switches for further extending the telephone connection from said junction line, registers for controlling the setting of said automatic switches, automatic switching means for connecting an idle register to a junction line, means under the control of a register for causing this register to be automatically connected to a disengaged junction, immediately upon the register being set free for other connections, and means under the control of a register for marking the junction as accessible to said selecting means upon a register being connected up to said junction line.

In testimony whereof I affix my signature.

ROMAN TRECHCINSKI. 

